1. Field of the Invention
The present invention relates to a method for fabricating a hydrogenated silicon oxycarbide (H:SiOC) thin film, and in particular to a method for fabricating a hydrogenated SiOC thin film having low dielectric permitivity, which is capable of minimizing carbon loss although a thin film passes a following process such as an oxygen ashing, etc.
2. Description of the Prior Art
With the intergration of semiconductor device, because finer circuit structure is required, a horizontal interval between metal wiring formed on the same plane has to be reduced. However, when an interval of metal wiring is reduced, cross talk may occur between the metal wiring by a parasitic capacitance between them. In that case, an electric signal transmission through the metal wiring may not be performed well or transmission speed may be lowered. In order to improve a speed of signal transmission through the metal wiring, the parasitic capacitance between the metal wiring has to be low. Accordingly, insulating layers having low dielectric permitivity are required.
One of the insulating layers, a SiOC (silicon oxycarbide) thin film fabricated by retaining lots of carbon in the conventional SiO2 thin film comes to the front. The SiOC thin film can be formed by a CVD (chemical vapor deposition), herein, methylsilance, di-methylsilane, tri-methylsilane and tetra-methylsilane, etc. can be used in the CVD.
In the SiOC thin film, carbon retained in the thin film as CHn shape dangles about part of SiO2 having a mesh structure, and air hole having a nanometer size is formed by the dangling, herein, the air hole affects dielectric permitivity lowering. In addition, it is assumed that Sixe2x80x94CH3 bonding has smaller ionic polarizability than that of Sixe2x80x94O bonding, however, its mechanism has not been clarified accurately.
However, in the SiOC thin film, because an ashing process using oxygen is performed to eliminate a sensitizing solution hardened by a dry etching, a wet etching or an ionic injection, etc. and carbon loss in the thin film occurs by an additional following process, thin film characteristics may be lowered.
In order to solve the above-mentioned problems, it is an object of the present invention to provide a method for fabricating a hydrogenated SiOC (silicon oxycarbide) thin film which is capable of minimizing carbon loss although a thin film passes a following process such as an oxygen ashing.
In addition, it is another object of the present invention to provide a PECVD (plasma enhanced chemical vapor deposition) apparatus used in fabrication of the above-mentioned SiOC thin film.
A hydrogenated SiOC thin film fabrication method includes supplying BTMSM (bis-trimethylsilylmethane) and oxygen retaining gas to a wafer installed inside a reaction channel through one supply pipe, simultaneously or sequentially supplying hydrogen to the wafer through another supply pipe, applying RF power in the range of 100xcx9c2000 W while supplying those gases and generating plasma of those gases.
In the meantime, a PECVD (plasma enhanced chemical vapor deposition) apparatus in accordance with the present invention includes a reaction chamber; plural susceptors installed inside the reaction chamber and horizontally mounted with a wafer respectively; a heating means for heating the susceptors; a power supply unit installed outside of the reaction chamber; a plasma electrode receiving RF power from the power supply unit, generating and maintaining plasma inside the reaction chamber; and a rotation jet spray having two spray injectors horizontally rotating and supplying gas inside the reaction chamber.
The rotation jet spray includes a cylinder vertically combined with the upper wall of the reaction chamber, having two ring-shaped grooves formed along the inner circumference and respectively connected to two gas injection holes penetrating the side wall of the ring-shaped groove; a rotational shaft vertically disposed inside the reaction chamber by being inserted into the cylinder to perform a rotation motion in a state adhered closely to the internal wall of the cylinder and having two gas supply pipes parallel to the length direction and connected to the ring-shaped grooves; and tube-shaped two spray injectors horizontally installed so as to be respectively connected to the gas supply pipes at the insertion end of the rotational shaft to perform a horizontal rotation by the rotation of the rotational shaft and having plural injection holes at the lower portion.
It is preferable for the two spray injectors to face each other centering around the center of the rotational shaft.
Oxygen can be used as the oxygen retaining gas, and it is preferable to deposit a thin film by rotating the spray injector at the speed of 1xcx9c100 rpm.